Method for positioning a sewing machine needle



Oct. 28, 1958 D. BAUM 2,857,868

METHOD FOR POSITIONING A SEWING MACHINE NEEDLE Filed Dec. 10, 1953 E INVENTOR 0/! W0 BA UM AT NEY Unite METHOD FOR POSITIONING A SEWING MACHINE NEEDLE This invention relates to a method and apparatus for positioning a sewing machine needle to prevent deflection thereof under stress exerted by the operator.

in the use of numerous types of sewing machines it has been found that there is a tendency on the part of the operators to push or pull the work through the machine, which tendency has no deleterious effect on the needle so long as the work is firmly held between the feed dog and presser foot of the machine. However, during that portion of the sewing cycle when the feed dog drops below the level of the throat plate out of engagement with the work and the point of the needle has passed through the work, any pushing or pulling of the work will exert a stress on the needle causing the latter to spring or bend. If the force applied to the needle is very great, it will snap the needle in two. Even in the case where the needle is not sprung to the point of snapping, the deflection of the needle changes the relative positions of the needle and the thread looper, resulting in skipping or breaking of the thread, thereby producing an inferior sewing job.

It is an object of this invention, therefore, to provide a method for flexing the needle of the sewing machine a predetermined distance during that portion of the sewing cycle when the feed dog is disengaged from the work, and prior to the exertion of stress on the needle by the operator, thereby preventing further springing of the needle when the work is pushed or pulled through the machine and maintaining at all times the correct position of the needle with respect to the thread looper.

Another object of this invention is to provide a sewing machine attachment for flexing or springing the sewing machine needle during a portion of the sewing cycle, the movement of which attachment is synchronized with the operation of the other moving components of the machine.

A further object of the invention is to provide a sewing machine attachment for flexing or springing the sewing machine needle, which attachment may be readily attached to the machine and is easily adjustable both in the vertical and horizontal directions.

The invention, together with its objects and advantages, will be best understood by reading the following detailed description with reference to the accompanying drawing in which is illustrated a presently preferred embodiment of the invention, and wherein:

Fig. 1 is a perspective view of the sewing machine attachment forming a part of the present invention;

Fig. 2 is a similar view of the same, looking at the front of the deflector;

Fig. 3 is a fragmentary side elevational view of a sewing machine illustrating the application of the present device and showing the initial position assumed by the moving components of the machine, the throat plate and work support being removed to disclose details of structure;

Fig. 4 is the same as Fig. 3 and illustrates the second or work-engaging phase of the sewing cycle;

atent M 2,857,868 Patented Oct. 28, 1958 Fig. 5 is the same as Fig. 3 and illustrates the third or deflecting phase of the sewing cycle, and

Fig. 6 is the same as Fig. 3 and illustrates the final or withdrawal phase of the sewing cycle.

Referring now to Figs. '5 to 6 of the drawing, I have shown the device of the present invention applied to a conventional Union Special sewing machine which comprises a needle "I threadedly engaged at 8 to a needle bar 9. Functioning synchronously with the operation of needle 7 are a threadlooper ill, a presser foot 11 and a feed dog 12 between the latter two of which the work to he sewed is fed. Presser foot 11 is secured in conventional manner to a presser arm 13 while feed dog 12 is secured to shank 14. Shank i4 is connected to, and movable with, feed bar 15. Adjacent feed dog 12 is a throat plate support 16 which is secured to a stationary part of the machine by member 17.

Slidably mounted between guides 18, mounted on one face of shank lid, is a mounting plate 19. Plate 19 is vertically adjustable by means of an adjustment screw 20 and nut 21, the former of which is threadedly engaged with a sleeve 22 secured to shank l4. Adjustably mounted on plate 19 by means of a set screw 23 is a needle deilector 24 which may be L-shaped. As indicated at 25 one arm of deflector 24 is centrally slotted from one terminus to a point beyond its midpoint, for the reception of set screw 23, thereby permitting horizontal adjustment of deflector 24. Thus deflector 24, may be horizontally and vertically adjusted to accommodate diflerent sized needles and effect any desired flexing of needle 7.

in operation, needle '7 is initially in the position shown in Pig. 3, at which time presser foot 11 and feed dog i2 engage the work. The needle then passes through the work to the position shown in Pig. 4. Presser foot Ill and feed dog 12 continue to grip the work, thereby preventing any movement of the work and consequent bending of needle 7 under stress by the operator. Needle 7 continues its downward stroke to the lowermost point in its cycle, shown in Fig. 5, at which time feed dog 12 is disengaged from the work for the first time. it is at this point in the cycle that needle deflector operating synchronously with feed dog 12, moves laterally into engagement with needle 7, springing the latter a predetermined amount. Since presser foot Ill and feed dog 12 no longer prevent movement of the work under urging of the operator, any pulling or pushing force on the work will be transmitted to needle 7. However, needle deflector 24 positively precludes the movement of needle 7 in the direction of shank M and, by springing needle 7 in the direction opposite shank 14-, to a degree approaching the elastic limit of the needle, the latter is able to withstand any lateral stress that may be exerted on it by the work. Experiment has shown that optimum results are obtained when the needle is deflected approximately one-sixteenth of an inch. As the needle ascends, it engages thread looper ill which is so adjusted to engage the needle while the latter is in the deflected position. in Fig. 6 there is shown the Withdrawal. phase of the cycle in which needle 7 rises out of engagement with needle deflector 24 and feed dog 12 reengages the work to once again retain the latter against movement under force exerted thereon by the operator.

While the present invention has been shown and described in connection with a Union Special sewing machine, it is to be understood that such has been done for purposes of illustration only and not by way of limitation, and therefore only such limitations are to be imposed thereon as may reasonably come within the scope of the appended claims.

What I claim is:

1. A method for positioning a sewing machine needle to prevent deflection thereof under stress exerted on the Work by the operator, comprising the steps of springing the needle a predetermined amount in the plane of stress exerted on the needle by the work, when the feed dog of the machine drops out of engagement with the work, and releasing the needle when the feed dog re-engages the work.

2. A method for positioning a sewing machine needle to prevent deflection thereof under stress exerted on the work by the operator, comprising the steps of springing the needle in the plane of stress exerted on the needle by the work to a point approximating the elastic limit of the needle, when the feed dog of the machine drops out of engagement with the work, and releasing the needle when the feed dog re-engages the work.

3. A method for positioning a sewing machine needle to prevent deflection thereof under the pushing and pulling stress exerted on the work by the operator, comprising the steps of springing the needle in the direction exerted thereon by the pulling stress when the feed dog of the machine drops out of engagement with the work, locating the thread looper to take the needle loop when the needle is in the sprung position, and releasing the needle when the feed dog re-engages the work.

References Cited in the file of this patent UNITED STATES PATENTS 657,400 Dimond et al. Sept. 4, 1900 898,403 Corey Sept. 8, 1908 934,954 Woodward Sept. 21, 1909 1,134,528 Hansen Apr. 6, 1915 2,496,243 Clayton Jan. 31, 1950 

